outside playtime

I got my first chicks..Rhode Island Red. They are a week old. My question is I put together a 7' x 7' "garden" fence area which I want to take my babies outside for a couple hours to play LOL .
I will be out there with them but it is in an area where the wind has blown dried horse pattys. I cleared out the biggest ones but there is still some and hay that has been covered by blowing sand.
Will taking them outside hurt them? The temps are in the mid 70s.

I had my birds out at about day 4 or 5 as long as it was warm. They are almost 2 weeks now and are outside almost every day from 8am-6pm. I even converted a rabbit pen for them so they could stay out in a bigger space. Here are my cornish crosses today in their new pen.